Question

arrange the following atoms in order of decreasing atomic radius: ga, as, sn, sb, te
a te, sb, sn, as, ga
b ga, as, sn, sb, te
c te, sb, as, sn, ga
d sn, sb, te, ga, as
e sn, sb, te, as, ga

Explanation:

Step1: Recall atomic - radius trends

Atomic radius decreases across a period (left - to - right) and increases down a group. Ga (gallium), As (arsenic) are in the fourth period with Ga in group 13 and As in group 15. Sn (tin), Sb (antimony), Te (tellurium) are in the fifth period with Sn in group 14, Sb in group 15 and Te in group 16.

Step2: Compare atoms in the same period

In the fourth period, Ga has a larger atomic radius than As because atomic radius decreases from left to right across a period. In the fifth period, Sn > Sb > Te for the same reason.

Step3: Compare atoms from different periods

Atoms in the fifth period (Sn, Sb, Te) have larger atomic radii than atoms in the fourth period (Ga, As) because the principal quantum number \(n\) is larger for the fifth - period atoms, leading to a larger electron cloud.

Answer:

d. Sn, Sb, Te, Ga, As